1. Field of the Invention
The invention relates to a physiological test probe of the type which may be used to derive foetal electrocardiograms.
2. Description of the Prior Art
Test probes of this type are by their basic construction appropriate for picking up the foetal electrocardiogram throughout the whole of the birth process. According to Edward H. Hon, Amer. J. Obstet. Gynec. Vol. 86, 1963, page 773 a test probe of this kind is constructed as a vaginal electrode with contact points by modifying a suture clip and adapting it to be applied by means of forceps. In principle we are here dealing with a needle electrode. In other words, it presupposes a comparatively deep penetration of the point into the skin of the foetal head. Such a clip can be detached only with considerable difficulty prior to the actual birth of the child. Moreover, in view of the open-and shut-bending action it is not suitable for repeated use, as was found by H. W. Junge, 9, Geburtshilfe und Frauenheilkunde 29.2. page 133.
Also known, according to Edward H. Hon, Yale Journal of Biology and Medicine, Vol. 32, April, 1960, are resilient needle-shaped electrodes which partly slide past one another with their contact points and thereby are liable to damage tissues. The contact points penetrate into the head skin or scalp due to the closing of a clip and a derivation cable is attached to said clip. The counter electrode terminates exposed at a point which is insulated relative to said clip so that there is a contact with the mother. Also, according to Charles A. Hunter, Kenneth G. Lansford, Suzanne B. Knoebel and Robert J. Braunlin, Obstetrics and Gynecology, Vol. 16, 1960, page 567, the clip may be replaced by a spring. In that case the spring is slidably arranged in a guide tube from which project only the frontal sections with the angled contact points. However, in order to close the clip or to close the spring it is always necessary to apply additional forces which makes unnecessarily severe demands on the concentration of the attending doctor in actual birth conditions.